Caterpillar, Inc., the assignee of this invention, has invented real time methods and systems for precisely determining the position of a mobile geography-altering machine as it traverses a work site and for creating a dynamically updated digital model of the site as it is altered by the machine. These systems improve the ability of an operator or site supervisor to monitor and control the operation of a single machine on the work site.
The Caterpillar systems use a digital data storage, retrieval and process facility which may be carried on the machine for storing, creating and modifying a digital model of the site as it exists at any given time, as well as a digital model of the desired geography of the site. They further use a mechanism by which the exact position in three-dimensional space of the machine, or its operative portion, can be accurately determined in real time; i.e., as it traverses and alters the site thereby to update the site model, point by point and in real time. In a preferred implementation a phase differential GPS (global positioning system) receiver system is used which is capable of precisely locating a moving object in three-dimensional space to centimeter accuracy. The digital process facility, e.g. a local computer, includes a dynamic site database and differencing algorithm which compares the desired site model to the continuously updated actual site model and generates signals representing the degree of alteration needed at each of a large number of coordinates over the site to bring the actual model into conformity with the desired model. The signals are used in one practical application to provide real time displays on the machinery to cue the operator as to the machine's actual position and progress in real time and within a frame of reference which conveys information as to at least a substantial portion of the overall site.
The site, or a practically displayable portion thereof, is subdivided into a continuous matrix of unit areas of such size that the machine may traverse these unit areas at a rate which is greater than the sampling rate of the GPS receiver and data processing facility. Algorithms are provided which take into account the physical parameters and dimensions of at least an operative portion of the machine and the relationship thereof to the machine in its path of travel. The unit areas of the display are filled in, colored, revised or otherwise altered in accordance with progress information derived from the GPS receiver and the digital processing facility. The real time path of the machine relative to the site between position readings is determined with a differencing algorithm which determines effective parameters of the operative portion of the machine less than or equal to its actual parameters, and which updates each portion of the site model which the effective parameters traverse.
The present invention provides a solution to the previously unaddressed problem of coordinating multiple geography-altering machines as they operate on a common work site, in particular where the machines are equipped with real time three-dimensional positioning capability and their operations are directed with a dynamically updated site database used to monitor machine position and site progress in real time.